Lorvotuzumab mertansine is an antibody-drug conjugate (ADC) combining an anti-NCAM1 (CD56) monoclonal antibody with the maytansinoid DM1 (PubChem CID 71301226) tubulin inhibitor [2].Annotated peptide sequences for this antibody are available from its IMGT/mAb-db record. Patent US5639641 [4] describes the resurfacing of murine anti-CD56 monoclonal antibody N901, to improve its therapeutic efficacy in preparation for use as a human drug. A protein BLAST search matches the variable region of the light chain of lorvotuzumab, with sequence 36 from the patent, sequence 36 being a CDR grafted version of N901. No affinity data for the interaction between the preferred engineered antibody and the molecular target is provided in the patent.